Maximillian Robespierre was one of the revolutionary of French Revolution of 1789, he was a lawyer (by profession) from Arras. Eugene De Rastignac was also moved to Madame Vaquer’s house in order to study Law. Maximillian Robespirre had sisters and a younger brother, so did Balzac’s Rastignac had two sisters and a younger brother.
It is often said and was observed that Robespierre was not revolutionary from very childhood, after the death of their father and mother Maximillian became the head and responsible man of his family. It is said that he was a student who wanted to educate himself, he was once selected by the school to read the poem before King Louis XVI.
Rastignac was also a normal student who wanted to educate himself in the field of Law, he moved from country to Madame Vaquer’s apartment so that he could be near to Paris and be in good society for education.
Rousseau and The Revolution changed Robespierre forever, he let himself to be changed and became what he or others could never even think of. Rastignac let himself to be changed by the flamboyant lifestyle of Paris, the thing to be noted over here is both were young. Rastignac after learning about the reality of Father Goriot became so much sympathetic and care some for him the way Robespierre became a Jacobin for the uplift-ment of the Third Estate.
Honore De Balzac mention the events of Revolution a few times in the novel, the way Father Goriot earned money and condition of Vautrine. I’m quite inclined that Rastignac was inspired from Robespierre.